Summary The purpose of this proposal is to provide equipment support to our currently funded NIGMS (R35GM118159) research project. The goal of this study is to explore community dynamics of the gut microbiota using gnotobiotic mouse models, with a focus on interbacterial antagonism and microbial dysbiosis. Gnotobiotic animals provide a unique opportunity to study interactions between wildtype and genetically manipulated human gut symbionts to better understand community dynamics of commensal bacteria. They also provide the platform by which to understand how the modulation of the microbiota by the host may contribute to dysbiosis as well as how bacterial enzymes impact medicinal drug metabolism. In order to accomplish the goals of the parent grant, we have established a successful germ-free facility using plastic flexible film isolators in which we are able to conduct a wide range of experimental techniques, including germ-free rederivation, under environmentally controlled conditions. These studies are providing key mechanistic insights that expand our understanding of the impact of the gut on human health. We have made significant progress in our research, producing 9 papers in the past 3 years supported by the parent grant. There are limitations to performing gnotobiotic experiments in isolators, most notably space and microbiome constraints. Our model requires multiple experimental conditions, timepoints and multiple gnotobiotic mice for each condition and timepoint. Our experiments are restricted by these limitations and therefore prevent us from addressing key questions that have emerged from our studies to date. In order to overcome this limitation, technologies are readily available that would expand our gnotobiotic facility beyond flexible film isolators. The sealed positive pressure (SPP) isocage system is an individually ventilated cage (IVC) positive containment system that would allow each individual cage to function as an experimental group. It consists of 3 modules that work together to house, sterilize and perform gnotobiotic experiments. It would allow us to streamline experimental setup of germ-free mice reared in flexible film isolators and allow for more flexibility with experimental design while still maintaining the barrier containment required of gnotobiotic work. This system would ultimately allow us to maximize our experimental potential for each of our research projects and better fulfill the needs of our parent grant.